scholarly journals Analysis of reactive bromine production and ozone depletion in the Arctic boundary layer using 3-D simulations with GEM-AQ: inference from synoptic-scale patterns

2011 ◽  
Vol 11 (8) ◽  
pp. 3949-3979 ◽  
Author(s):  
K. Toyota ◽  
J. C. McConnell ◽  
A. Lupu ◽  
L. Neary ◽  
C. A. McLinden ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Ozone Depletion ◽  
Surface Ozone ◽  
High Arctic ◽  
Heterogeneous Reactions ◽  
The Arctic ◽  
Synoptic Scale ◽  
Arctic Boundary Layer ◽  
Surface Snow

Abstract. Episodes of high bromine levels and surface ozone depletion in the springtime Arctic are simulated by an online air-quality model, GEM-AQ, with gas-phase and heterogeneous reactions of inorganic bromine species and a simple scheme of air-snowpack chemical interactions implemented for this study. Snowpack on sea ice is assumed to be the only source of bromine to the atmosphere and to be capable of converting relatively stable bromine species to photolabile Br2 via air-snowpack interactions. A set of sensitivity model runs are performed for April 2001 at a horizontal resolution of approximately 100 km×100 km in the Arctic, to provide insights into the effects of temperature and the age (first-year, FY, versus multi-year, MY) of sea ice on the release of reactive bromine to the atmosphere. The model simulations capture much of the temporal variations in surface ozone mixing ratios as observed at stations in the high Arctic and the synoptic-scale evolution of areas with enhanced BrO column amount ("BrO clouds") as estimated from satellite observations. The simulated "BrO clouds" are in modestly better agreement with the satellite measurements when the FY sea ice is assumed to be more efficient at releasing reactive bromine to the atmosphere than on the MY sea ice. Surface ozone data from coastal stations used in this study are not sufficient to evaluate unambiguously the difference between the FY sea ice and the MY sea ice as a source of bromine. The results strongly suggest that reactive bromine is released ubiquitously from the snow on the sea ice during the Arctic spring while the timing and location of the bromine release are largely controlled by meteorological factors. It appears that a rapid advection and an enhanced turbulent diffusion associated with strong boundary-layer winds drive transport and dispersion of ozone to the near-surface air over the sea ice, increasing the oxidation rate of bromide (Br−) in the surface snow. Also, if indeed the surface snowpack does supply most of the reactive bromine in the Arctic boundary layer, it appears to be capable of releasing reactive bromine at temperatures as high as −10 °C, particularly on the sea ice in the central and eastern Arctic Ocean. Dynamically-induced BrO column variability in the lowermost stratosphere appears to interfere with the use of satellite BrO column measurements for interpreting BrO variability in the lower troposphere but probably not to the extent of totally obscuring "BrO clouds" that originate from the surface snow/ice source of bromine in the high Arctic. A budget analysis of the simulated air-surface exchange of bromine compounds suggests that a "bromine explosion" occurs in the interstitial air of the snowpack and/or is accelerated by heterogeneous reactions on the surface of wind-blown snow in ambient air, both of which are not represented explicitly in our simple model but could have been approximated by a parameter adjustment for the yield of Br2 from the trigger.

scholarly journals Synoptic-scale meteorological control on reactive bromine production and ozone depletion in the Arctic boundary layer: 3-D simulation with the GEM-AQ model

2010 ◽  
Vol 10 (11) ◽  
pp. 26207-26278 ◽  
Author(s):  
K. Toyota ◽  
J. C. McConnell ◽  
A. Lupu ◽  
L. Neary ◽  
C. A. McLinden ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Dry Deposition ◽  
Ozone Depletion ◽  
Surface Ozone ◽  
High Arctic ◽  
Heterogeneous Reactions ◽  
The Arctic ◽  
Synoptic Scale ◽  
Arctic Boundary Layer

Abstract. Episodes of high bromine levels and surface ozone depletion in the springtime Arctic are simulated by an online air-quality model, GEM-AQ, with gas-phase and heterogeneous reactions of inorganic bromine species and a simple scheme of air-snowpack chemical interactions implemented for this study. Snowpack on sea ice is assumed to be the only source of bromine to the atmosphere and capable of converting relatively stable bromine species to photolabile Br2 via air-snowpack interactions. A "bromine explosion", by which Br− retained in the snowpack is autocatalytically released to the atmosphere as a result of dry deposition of HOBr and BrONO2, is assumed to occur on young, first-year (FY) sea ice (or its overlying snowpack), whereas the snowpack on old, multi-year (MY) sea ice and over land is assumed only to recycle a part (but up to 100%) of bromine reservoirs lost via dry deposition back to Br2. Model runs are performed for April 2001 at a horizontal resolution of approximately 100 km × 100 km in the Arctic. The model simulates temporal variations in surface ozone mixing ratios as observed at stations in the high Arctic and the synoptic-scale evolution of enhanced BrO column amounts ("BrO clouds") as seen from satellite reasonably well. The results strongly suggest: (1) a ubiquitous source of reactive bromine exists on the FY sea ice during the Arctic springtime; and (2) the timing of bromine release to the atmosphere is largely controlled by meteorological forcing on the transport of ozone to the near-surface air. Also, if the surface snowpack supplies most of the reactive bromine in the Arctic boundary layer, it should be capable of releasing reactive bromine at temperatures as high as −10 °C, particularly on the FY sea ice in the central and eastern Arctic Ocean. Dynamically-induced BrO column variability in the lowermost stratosphere appears to interfere with the use of satellite BrO column measurements for interpreting BrO variability in the lower troposphere but probably not to the extent of totally obscuring "BrO clouds" associated with the surface source of bromine in the high Arctic. Contrary to our original intention, the present air-snowpack interaction scheme yields a majority of atmospheric bromine input via Br2 release associated empirically with a dry deposition of ozone on the snow/ice surface under sunlight to represent a trigger of bromine explosion. This implies that the bromine explosion actually occurs in the interstitial air of snowpack and/or is accelerated by heterogeneous reactions on the surface of wind-blown snow in ambient air, both of which are missing in our model but could have been approximated by a parameter adjustment for the yield of Br2 from the trigger.

scholarly journals Signature of Arctic surface ozone depletion events in the isotope anomaly (Δ<sup>17</sup>O) of atmospheric nitrate

2007 ◽  
Vol 7 (5) ◽  
pp. 1451-1469 ◽  
Author(s):  
S. Morin ◽  
J. Savarino ◽  
S. Bekki ◽  
S. Gong ◽  
J. W. Bottenheim
Keyword(s):  
Boundary Layer ◽  
Ozone Depletion ◽  
Surface Ozone ◽  
The Arctic ◽  
Arctic Boundary Layer ◽  
Mixing Ratios ◽  
Atmospheric Nitrate ◽  
Boundary Layer Ozone ◽  
Oxidation Of No ◽  
Arctic Surface

Abstract. We report the first measurements of the oxygen isotope anomaly of atmospheric inorganic nitrate from the Arctic. Nitrate samples and complementary data were collected at Alert, Nunavut, Canada (82°30 ' N, 62°19 ' W) in spring 2004. Covering the polar sunrise period, characterized by the occurrence of severe boundary layer ozone depletion events (ODEs), our data show a significant correlation between the variations of atmospheric ozone (O3) mixing ratios and Δ17O of nitrate (Δ17O(NO−3)). This relationship can be expressed as: Δ17O(NO−3)/‰, =(0.15±0.03)×O3/(nmol mol–1)+(29.7±0.7), with R2=0.70(n=12), for Δ17O(NO−3) ranging between 29 and 35 ‰. We derive mass-balance equations from chemical reactions operating in the Arctic boundary layer, that describe the evolution of Δ17O(NO−3) as a function of the concentrations of reactive species and their isotopic characteristics. Changes in the relative importance of O3, RO2 and BrO in the oxidation of NO during ODEs, and the large isotope anomalies of O3 and BrO, are the driving force for the variability in the measured Δ17O(NO−3) . BrONO2 hydrolysis is found to be a dominant source of nitrate in the Arctic boundary layer, in agreement with recent modeling studies.

scholarly journals Polar boundary layer bromine explosion and ozone depletion events in the chemistry-climate model EMAC v2.52: Implementation and evaluation of AirSnow algorithm

2017 ◽  
Author(s):  
Stefanie Falk ◽  
Björn-Martin Sinnhuber
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Atmospheric Chemistry ◽  
Dry Deposition ◽  
Ozone Depletion ◽  
Climate Model ◽  
Surface Ozone ◽  
The Arctic ◽  
Vertical Column ◽  
Model Studies

Abstract. Ozone depletion events (ODE) in the polar boundary layer have been observed frequently during spring-time. Most likely, they are related to events of boundary layer enhancement of bromine. Consequently, increased vertical column densities (VCD) of BrO have been observed from satellites. These so called bromine explosion events have been discussed serving as source of tropospheric BrO at high latitudes. We have implemented a treatment of bromine release and recycling on sea ice and snow covered surfaces in the global chemistry-climate model EMAC (ECHAM/MESSy Atmospheric Chemistry) based on the scheme of Toyota et al. (2011). In this scheme, dry deposition fluxes of HBr, HOBr, and BrNO3 over ice and snow covered surfaces are recycled into Br2 fluxes. In addition, dry deposition of O3, dependent on temperature and sunlight, triggers a Br2 release from surfaces associated with first-year sea ice. Many aspects of observed bromine enhancements and associated episodes of near-complete depletion of boundary layer ozone, both in the Arctic and in the Antarctic, are reproduced by this relatively simple approach. We present first results from our global model studies extending over a full annual cycle, including comparisons with GOME satellite BrO VCD and surface ozone observations.

scholarly journals Pronounced signature of arctic surface ozone depletion events after polar sunrise on Δ<sup>17</sup>O in atmospheric nitrate

2006 ◽  
Vol 6 (4) ◽  
pp. 6255-6297 ◽  
Author(s):  
S. Morin ◽  
J. Savarino ◽  
S. Bekki ◽  
S. Gong ◽  
J. W. Bottenheim
Keyword(s):  
Boundary Layer ◽  
Ozone Depletion ◽  
Surface Ozone ◽  
Ice Cores ◽  
The Arctic ◽  
Atmospheric Ozone ◽  
Ozone Level ◽  
Arctic Boundary Layer ◽  
Mixing Ratios ◽  
Boundary Layer Ozone

Abstract. We report in this paper the first measurements of the isotopic anomaly of oxygen in Arctic atmospheric inorganic nitrate. Data and samples were collected at Alert, Nunavut, Canada (82°30' N, 62°19' W) in spring 2004. Focusing on the polar sunrise period, characterized by the occurrence of severe boundary layer ozone depletion events (ODEs), our data show a significant correlation between the evolution of atmospheric ozone (O3) mixing ratios and Δ17O in nitrate Δ17O(NO−3)). This relationship can be expressed as: Δ17O(NO−3)/‰=0.15 O3/ (nmol mol−1) + 28.6, with R2=0.70 (n=12), for Δ17O(NO−3) ranging between 29 and 34. To quantitatively interpret this relationship, we derive from mechanisms at play in the arctic boundary layer isotopic mass-balance equations, which depend on the concentrations of reactive species and their isotopic characteristics. Changes in the relative importance of O3, RO2 and BrO in the oxidation of NOx during ODEs, and the large isotopic anomalies that O3 and BrO carry, are the driving force for the high variability in the measured Δ17O(NO−3). BrONO2 hydrolysis is found to be the major source of nitrate in the arctic boundary layer, in agreement with recent modeling studies. In addition, the isotopic fingerprint of the activity of ozone in a relatively stable compound appears somewhat promising in the perspective of using the isotopic composition of nitrate embedded in polar ice-cores as a paleo-indicator of the atmospheric ozone level that may yield an indirect proxy for the oxidative power of past atmospheres.

scholarly journals Polar boundary layer bromine explosion and ozone depletion events in the chemistry–climate model EMAC v2.52: implementation and evaluation of AirSnow algorithm

2018 ◽  
Vol 11 (3) ◽  
pp. 1115-1131 ◽  
Author(s):  
Stefanie Falk ◽  
Björn-Martin Sinnhuber
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Atmospheric Chemistry ◽  
Dry Deposition ◽  
Ozone Depletion ◽  
Climate Model ◽  
Surface Ozone ◽  
The Arctic ◽  
In Situ Observation ◽  
Vertical Column

Abstract. Ozone depletion events (ODEs) in the polar boundary layer have been observed frequently during springtime. They are related to events of boundary layer enhancement of bromine. Consequently, increased amounts of boundary layer volume mixing ratio (VMR) and vertical column densities (VCDs) of BrO have been observed by in situ observation, ground-based as well as airborne remote sensing, and from satellites. These so-called bromine explosion (BE) events have been discussed serving as a source of tropospheric BrO at high latitudes, which has been underestimated in global models so far. We have implemented a treatment of bromine release and recycling on sea-ice- and snow-covered surfaces in the global chemistry–climate model EMAC (ECHAM/MESSy Atmospheric Chemistry) based on the scheme of Toyota et al. (2011). In this scheme, dry deposition fluxes of HBr, HOBr, and BrNO3 over ice- and snow-covered surfaces are recycled into Br2 fluxes. In addition, dry deposition of O3, dependent on temperature and sunlight, triggers a Br2 release from surfaces associated with first-year sea ice. Many aspects of observed bromine enhancements and associated episodes of near-complete depletion of boundary layer ozone, both in the Arctic and in the Antarctic, are reproduced by this relatively simple approach. We present first results from our global model studies extending over a full annual cycle, including comparisons with Global Ozone Monitoring Experiment (GOME) satellite BrO VCDs and surface ozone observations.

scholarly journals Reproducing springtime Arctic tropospheric ozone depletion events in an outdoor mesocosm sea-ice facility

2021 ◽  
Author(s):  
Zhiyuan Gao ◽  
Nicolas-Xavier Geilfus ◽  
Alfonso Saiz-Lopez ◽  
Feiyue Wang
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Gas Phase ◽  
Ozone Depletion ◽  
Surface Ozone ◽  
Environmental Research ◽  
The Arctic ◽  
Ozone Loss ◽  
Ozone Concentrations ◽  
Air Temperatures

Abstract. The episodic build-up of gas-phase reactive bromine species over sea ice and snowpack in the springtime Arctic plays an important role in the boundary layer, causing annual concurrent depletion of ozone and gaseous elemental mercury during polar sunrise. Extensive studies have shown that these phenomena, known as bromine explosion events (BEEs), ozone depletion events (ODEs) and mercury depletion events (MDEs), respectively, are all triggered by gas-phase reactive bromine species that are photochemically activated from bromide via multi-phase reactions under freezing air temperatures. However, major knowledge gaps exist in both fundamental cryo-photochemical processes causing these events and meteorological conditions that may affect their timing and magnitude. Here, we report an outdoor mesocosm-scale study in which we successfully reproduced ODEs at the Sea-ice Environmental Research Facility (SERF) in Winnipeg, Canada. By monitoring ozone concentrations inside large, acrylic tubes over bromide-enriched artificial seawater during entire sea ice freeze-and-melt cycles, we observed mid-day photochemical ozone loss in winter in the boundary layer air immediately above the sea ice surface in a pattern that is characteristic of BEE-induced ODEs in the Arctic. The importance of UV radiation and the presence of a condensed phase (experimental sea ice or snow) in causing such surface ozone loss was demonstrated by comparing ozone concentrations between UV-transmitting and UV-blocking acrylic tubes under different air temperatures. The ability of reproducing BEE-induced ODEs at a mesocosm scale in a non-polar region provides a new approach to systematically studying the cryo-photochemical and meteorological processes leading to BEEs, ODEs, and MDEs in the Arctic, their role in biogeochemical cycles across the ocean-sea ice-atmosphere interfaces, and their sensitivities to climate change.

scholarly journals Ozone in the Boundary Layer air over the Arctic Ocean – measurements during the TARA expedition

2009 ◽  
Vol 9 (2) ◽  
pp. 8561-8586
Author(s):  
J. W. Bottenheim ◽  
S. Netcheva ◽  
S. Morin ◽  
S. V. Nghiem
Keyword(s):  
Boundary Layer ◽  
Arctic Ocean ◽  
Ozone Depletion ◽  
Surface Ozone ◽  
The Arctic ◽  
Total Absence ◽  
Trajectory Calculations ◽  
The Arctic Ocean ◽  
Ocean Measurements ◽  
Siberian Coast

Abstract. A full year of measurements of surface ozone over the Arctic Ocean far removed from land is presented (81° N – 88° N latitude). The data were obtained during the drift of the French schooner TARA between September 2006 and January 2008, while frozen in the Arctic Ocean. The data confirm that long periods of virtually total absence of ozone occur in the spring (mid March to mid June) after Polar sunrise. At other times of the year ozone concentrations are comparable to other oceanic observations with winter mole fractions of ca. 30–40 nmol mol−1 and summer minima of ca. 20 nmol mol−1. Contrary to earlier observations from ozone sonde data obtained at Arctic coastal observatories, the ambient temperature was well above −20°C during most ODEs (ozone depletion episodes). Backwards trajectory calculations suggest that during these ODEs the air had previously been in contact with the frozen ocean surface for several days and originated largely from the Siberian coast where several large open flaw leads developed in the spring of 2007.

scholarly journals The role of open lead interactions in atmospheric ozone variability between Arctic coastal and inland sites

Elem Sci Anth ◽  
2016 ◽  
Vol 4 ◽  
Author(s):  
Peter K. Peterson ◽  
Kerri A. Pratt ◽  
William R. Simpson ◽  
Son V. Nghiem ◽  
Lemuel X. Pérez Pérez ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Ozone Depletion ◽  
Surface Ozone ◽  
Optical Absorption Spectroscopy ◽  
Atmospheric Ozone ◽  
Vertical Profiles ◽  
Large Spatial Scale ◽  
Near Surface ◽  
Air Masses

Abstract Boundary layer atmospheric ozone depletion events (ODEs) are commonly observed across polar sea ice regions following polar sunrise. During March-April 2005 in Alaska, the coastal site of Barrow and inland site of Atqasuk experienced ODEs (O3&lt; 10 nmol mol-1) concurrently for 31% of the observations, consistent with large spatial scale ozone depletion. However, 7% of the time ODEs were exclusively observed inland at Atqasuk. This phenomenon also occurred during one of nine flights during the BRomine, Ozone, and Mercury EXperiment (BROMEX), when atmospheric vertical profiles at both sites showed near-surface ozone depletion only at Atqasuk on 28 March 2012. Concurrent in-flight BrO measurements made using nadir scanning differential optical absorption spectroscopy (DOAS) showed the differences in ozone vertical profiles at these two sites could not be attributed to differences in locally occurring halogen chemistry. During both studies, backward air mass trajectories showed that the Barrow air masses observed had interacted with open sea ice leads, causing increased vertical mixing and recovery of ozone at Barrow and not Atqasuk, where the air masses only interacted with tundra and consolidated sea ice. These observations suggest that, while it is typical for coastal and inland sites to have similar ozone conditions, open leads may cause heterogeneity in the chemical composition of the springtime Arctic boundary layer over coastal and inland areas adjacent to sea ice regions.

Pan-Arctic surface ozone seasonality modified by sea-ice-sourced bromine: modelling vs measurements

2021 ◽  
Author(s):  
Xin Yang ◽  
Anne-M Blechschmidt2 ◽  
Kristof Bognar ◽  
Audra McClure–Begley ◽  
Sara Morris ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Surface Ozone ◽  
Open Ocean ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Sea Spray ◽  
Research Station ◽  
Blowing Snow ◽  
Model Control

&lt;p&gt;Within the framework of the International Arctic Systems for Observing the Atmosphere (IASOA), we report a modelling-based study on surface ozone across the Arctic. We use surface ozone from six sites: Summit (Greenland), Pallas (Finland), Barrow (USA), Alert (Canada), Tiksi (Russia), and Villum Research Station (VRS) at Station Nord (North Greenland, Danish Realm), and ozonesonde data from three Canadian sites: Resolute, Eureka, and Alert. Two global chemistry models: a global chemistry transport model (p-TOMCAT) and a global chemistry climate model (UKCA), are used for model-data comparisons. Remotely sensed data of BrO from the GOME-2 satellite instrument at Eureka, Canada are used for model validation.&lt;/p&gt;&lt;p&gt;The observed climatology data show that spring surface ozone at coastal Arctic is heavily depleted, making ozone seasonality at Arctic coastal sites distinctly different from that at inland sites. Model simulations show that surface ozone can be greatly reduced by bromine chemistry. In April, bromine chemistry can cause a net ozone loss (monthly mean) of 10-20 ppbv, with almost half attributable to open-ocean-sourced bromine and the rest to sea-ice-sourced bromine. However, the open-ocean-sourced bromine, via sea spray bromide depletion, cannot by itself produce ozone depletion events (ODEs) (defined as ozone volume mixing ratios VMRs &lt; 10 ppbv). In contrast, sea-ice-sourced bromine, via sea salt aerosol (SSA) production from blowing snow, can produce ODEs even without bromine from sea spray, highlighting the importance of sea ice surface in polar boundary layer chemistry.&lt;/p&gt;&lt;p&gt;Modelled total inorganic bromine (Br&lt;sub&gt;Y&lt;/sub&gt;) over the Arctic sea ice &amp;#160;is sensitive to model configuration, e.g., under the same bromine loading, Br&lt;sub&gt;Y&lt;/sub&gt; in the Arctic spring boundary layer in the p-TOMCAT control run (i.e., with all bromine emissions) can be 2 times that in the UKCA control run. Despite the model differences, both model control runs can successfully reproduce large bromine explosion events (BEEs) and ODEs in polar spring. Model-integrated tropospheric column BrO generally matches GOME-2 tropospheric columns within ~50% in UKCA and a factor of 2 in p-TOMCAT. The success of the models in reproducing both ODEs and BEEs in the Arctic indicates that the relevant parameterizations implemented in the models work reasonably well, which supports the proposed mechanism of SSA production and bromide release on sea ice. Given that sea ice is a large source of SSA and halogens, changes in sea ice type and extent in a warming climate will influence Arctic boundary layer chemistry, including the oxidation of atmospheric elemental mercury. Note that this work dose not necessary rule out other possibilities that may act as a source of reactive bromine from sea ice zone.&lt;/p&gt;

Evaluating Arctic meteorology modelled with the Unified Model and Integrated Forecasting System

2020 ◽  
Author(s):  
Gillian Young ◽  
Jutta Vüllers ◽  
Peggy Achtert ◽  
Paul Field ◽  
Jonathan Day ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Weather Forecasting ◽  
Numerical Models ◽  
Model Performance ◽  
High Arctic ◽  
Unified Model ◽  
Surface Energy Budget ◽  
The Arctic ◽  
Forecasting System

&lt;p&gt;State-of-the-art numerical models such as the UK Met Office Unified Model and European Centre for Medium-Range Weather Forecasting Integrated Forecasting System are crucial tools for forecasting future Arctic warming. However, their ability to reproduce clouds and boundary layer meteorology in the high Arctic has not been thoroughly evaluated following significant model developments over the last 10 years. Model evaluation is key to understanding where remaining process weaknesses lie, thus informing further parametrization developments to improve the simulated surface energy budget.&lt;/p&gt;&lt;p&gt;Here, we evaluate model performance with comparison to observations made during the Arctic Ocean 2018 expedition, where a suite of remote-sensing instrumentation was active aboard the Swedish icebreaker &lt;em&gt;Oden &lt;/em&gt;measuring summertime Arctic cloud and boundary layer properties. We find that both models do not reproduce cloud fractions well at altitude (up to 8 km) and overestimate the occurrence of low (&lt;1 km) clouds during the sea ice melt period of the expedition. Low cloud agreement with observations improves when the sea ice begins to refreeze; however, the underestimation of cloud aloft remains consistent regardless of sea ice conditions. In this presentation, we will indicate which model processes need to be improved to capture these summertime Arctic clouds more effectively.&lt;/p&gt;

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